Cross-reference is made to two U.S. Pat. Applications: Ser. No. 044,767, for Added Array Of Molecular Chains For Interfering With Electric Fields, by W.D. Stanbro et al.; and Ser. No. 044,769, now U.S. Pat. No. 4,769,121, for Sintered Pellet With Biochemically Active Layer, by A.L. Newman, which were filed the same date and were assigned to the same entity as this application.
The invention relates to a means for interfering with an electrical field. More specifically, the invention relates to electrodes of a capacitive affinity sensor that are insulated with a three-dimensional molecular binding site array.
In composition analysis, capacitive sensors have been used to determine the concentration of a specific gas in a mixture, or an analyte in a fluid, for example. Such sensors measure a capacitance that changes with the concentration.
Newman U.S. Pat. Application Ser. No. 799,761, filed Nov. 19, 1985, ("the Newman Patent Application") involves a capacitor for determining the concentration of an analyte in a fluid, for instance. Biospecific binding reactions occur in a space between electrodes of a capacitive sensor. These reactions occur among molecules of a binding agent immobilized on a surface and an analyte in a fluid. These reactions result in the displacement of small fluid molecules having high dielectric constants by large biochemical molecules having low-dielectric constants. This displacement of molecules changes the dielectric constant of the capacitor.
Raymond et al. U.S. Pat. No. 4,571,543 discusses a capacitor for detecting and measuring the concentration of specific non aqueous materials or constituents in fluids. The capacitor is layered with a coating of silane and then a coating of certain polymers. These polymers form membranes that are permeable to constituents of the fluids. The constituents penetrate through the membrane to change the dielectric constant of a solution under the membrane.
Volgyesi U.S. Pat. No. 4,453,126 concerns a capacitor for monitoring the concentration of anaesthetic gas in a breathing mixture. The capacitor has a dielectric of lipids or elastomers which permit the absorption of the anaesthetic gas to vary electrical characteristics of the sensor.
"Adsorption Of Blood Proteins On Metals Using Capacitance Techniques", by Stoner et al., The Journal of Physical Chemistry, Vol. 74, No. 5, Mar. 5, 1970, describes a differential capacity method for measuring adsorption of proteins on solid metal electrodes.
Arwin et al. U.S. Pat. No. 4,072,576 relates to a capacitive method for studying enzymatic activity and for studying an immunological reaction. An adsorbed polypeptide substrate is used to study enzymatic activity and an antigen is adsorbed onto an electrode surface to study the reaction of the antigen with an antibody.
Molecular Design for Electroanalysis, by Murray et al., Analytical Chemistry, Vol. 59, No. 5, March 1, 1987, discusses chemically modified electrodes for use in sample analysis, and the use of electroactive polymer films, like poly-L-lysine, on such electrodes. These films facilitate oxidation-reduction reactions at the electrodes.
Kinetics of Electron-Transfer Cross-Reactions within Redox Polymers; Coatings of a Protonated Polylysine Copolymer with Incorporated Electroactive Anions, by Anson et al., Journal of the American Chemical Society, Vol. 105, No. 15, 1983, p. 4884, describes electrodes coated with polymer layers that form a three dimensional arrangement of catalytic sites. These layers comprise a random orientation of polymer coils to facilitate oxidation reduction reactions at the electrode. New Model for the Interior of Polyelectrolyte Coatings on Electrode Surfaces; Mechanisms of Charge Transport through Protonated Poly(L-lysine) Films Containing Fe.sup.III (edta)- and Fe.sup.II (edta).sup.2 - as Counterions, by Anson et al., Journal of the American Chemical Society, Vol. 105, No. 5, 1983, p. 1096, also describes such electrodes.
In composition analysis, affinity chromotography has been used to determine the presence or concentration of an analyte in a fluid. The analyte is chemically separated or isolated from the fluid, as described in two articles entitled "Affinity Chromotography", one by I. Parikh et al., Aug. 26, 1985, Chemical and Engineering News, pp. 17-32 and the other by R. Walters, Sept., 1985, Analytical Chemistry, Volume 57, No. 11, pp. 1099A-1114A.
Maggio et al. U.S. Pat. No. 4,233,402 deals with the chemical analysis of an analyte on a substrate using hub nuclei that spread along the substrate and to which ligands are covalently bound.